TORONTO, March 9 (Reuters) - The losing streak on Toronto’s main stock index extended to a third straight session on Wednesday as rising violence in Libya and concerns over debt-laden Portugal prompted nervous investors to lighten positions, dragging the market down nearly 1 percent.

The materials sector, home to miners, was the biggest drag on the index, sliding 2.25 percent as metals such as copper and zinc fell in response to rising oil prices. [GOL/] [MET/L]

“With the resource stocks, people are nervous about the economy because at some point, obviously, energy prices have an impact on the economy,” said Paul Hand, managing director at RBC Capital Markets.

Energy issues were also weaker, with the heavyweight sector down 0.97 percent, as investors questioned whether $100-plus oil would last, said Hand.

The Toronto Stock Exchange’s S&P/TSX composite index .GSPTSE ended down 128.26 points, or 0.92 percent, at 13,884.71, after opening slightly higher. Seven of its 10 main sectors finished in the red.

The TSX is still up 83.5 percent from its lowest close at the worst of the financial crisis, exactly two years ago, but the three-day retreat led the index to its lowest close since Feb. 24.

“There is so much uncertainty that people are trading the volatility rather than hanging on to any long-term positions,” said Azim Hajee, a senior market strategist at commodity futures brokerage Lind-Waldock Canada.

He said that investors were also nervous about euro zone debt levels, with fears growing that Portugal would need a bailout, despite its bond auction.

Portugal’s two-year cost of borrowing in Wednesday’s bond auction hit the highest level since the country joined the euro, and an official said yields were unsustainable in the long run without Europe-wide action. [ID:nLDE72814X]

Elsewhere, Viterra Inc VT.TO VTA.AX, Canada’s biggest grain handler and farm retailer, closed up 0.86 percent at C$11.20 after it posted its biggest-ever first-quarter profit on Wednesday, thanks to a record harvest in South Australia and high crop prices. [ID:nN08161193]

After the bell, auto parts maker Linamar Corp (LNR.TO) said it had a 32 percent rise in quarterly profit as it benefited from a continued recovery in the auto sector. It ended the session up 0.61 percent at C$21.38. [ID:nN09283444]